Grove heaters and the like



April 1967 H. E. SNODGRASS ETAL 3,315,723

GROVE HEATERS AND THE LIKE Filed Feb. 15, 1964 2 sheets-sheet 1 INVENTORS Ha rlan f. Snaayrass & Fz'cimm B. Wiley, Jr:

ATTORNEYS A- plll 25 QDGRASS ETAL 3,315,723 GROVE HEATERS AND THE LIKE Filed Feb. 15, 1964 2 Sheets-Sheet I;

. INVENTORS iE/ m Z United States Patent f 3,315,723 GRUVE HEATERS AND THE LIKE Harlan Eskey Snodgrass, Coral Gables, and Richard Baxter Wiiey, .lir., Miami, Fla, assignors to Belcher Oil Company, h iiiami, Fla, a corporation of Florida Filed Feb. 13, 1964, Ser. No. 344,765 3 Claims. (Cl. 153--91) This invention relates to heaters especially useful in protecting citrus groves, orchards, etc., from damage due to cold conditions beyond their tolerance. The problem of doing so is well known and important, because crop loss from year to year is enormous and seemingly practically impossible to avoid completely. It is desirable to provide a large number of heaters throughout the area of the trees, the heaters usually being of the oilburning type, and, depending upon the size of the grove, the number of heaters may run into many hundreds or even thousands. Accordingly with such large scale operations involved, and considering that it is often necessary to keep the heaters burning for days at a time, the cost to the grower is great, not only in initial burner cost, but also in fuel and the labor necessary for the task. From this it follows that any and all improvements in such heater construction leading to economy and efficiency are welcome and worthwhile contributions.

Because of the fact that in the large groves the available labor force is quite unskilled and unfamiliar with proper regulation and manipulation of the heaters, and also because of the large number of heaters needed, it is essential that heater construction be as simple and safe as possible. However, simplicity of construction does not usually go hand-in-hand with safety, and almost always simple heaters of the type heretofore proposed are difiicult, if not impossible, to operate on a highly eflicient basis.

The present invention is concerned with these problems as they are found in the type of heater which provides for an open-to-the-air oil surface which is ignited and burned. Heaters of this type provide a limited surface area, oil being supplied to the area from a reservoir surrounding a wall which itself defines the limits of the said area. This type of heater may take several physical forms. For example, such a heater may comprise inner and outer concentric walls and a closed bottom surface, the volume between the walls constituting an annular oil reservoir and the volume Within the inner wall containing oil, constantly gravity fed from the reservoir, and constituting the burning area. The top surface of the reservoir is closed but is vented to permit escape of fumes which collect at an increasing rate and volume as temperature rises and the oil level drops.

It is with respect to fume generation and disposition that this invention is especially directed, it being envisioned to 1) reduce the ever-present hazard to explosion resulting from the occurrence of an oxygen-hydrocarbon vapor mixture within the reservoir volume followed by ignition by the closely adjacent burning surface and (2) to utilize the hydrocarbon vapors continuously as a part of the heat supply to be provided for the grove. These important objectives are accomplished according to the present invention while, at the same time, providing a heater of most economical and easy-to-handle construction which may be employed to give off heat at a variety of desired rates by simple and easy interchange of heater parts.

The novel heater construction according to this invention is more fully described hereinafter and is illustrated by drawings wherein:

FIGURE 1 is an exploded view in perspective, partly broken away, showing the several parts of the heater;

3,315,723 Patented Apr. 25, 1967 FIGURE 2 is a vertical section, taken through the mid portion of the heater;

FIGURE 3 is a view in top plan showing the heater as viewed looking int-o the burner chamber.

Referring to FIGURE 1, numeral 10 indicates the heater section proper, numeral 12 indicates a regulator l0W-fire ring which is employed to reduce the rate of fuel consumption when desired, and numeral 14 indicates a cap, or cover, which is employed as a rain shield when the heater is not in use, and which may also be used to extinguish the heater flame.

Concerning the heater 10 more particularly, as seen in FIGURES 1 and 2, numeral 16 denotes the side wall and numeral 18 the bottom wall of the heater. Numeral 20 denotes an inner concentrically located burner tube which may be seen as resting upon the bottom 18. Numeral 22 denotes a top cover which, together with burner tube 20 defines an oil reservoir 24. The said top and burner tube meet at a number of points which may be defined as flutes, denoted by numeral 26, which are formed in the body wall of the tube. The spaces between said flutes are denoted by numeral 28 and define passageways leading from the interior of the reservoir. As will be seen, the top cover 22 is provided with an upwardly extending annular flange, denoted by numeral 30, which serves to prevent water from flowing from the broad surface area of the top into the oil reservoir.

The burner tube 20 is formed from a rectangular blank of sheet metal, the blank being first given the fluted surfaces. Preferably, the blank is of a flexible and spring nature so that it may readily be formed into the tubular configuration, and so as to retain its spring characteristics and tendency to return to its flat blank form to a strong extent. This manner of forming the tube permits it to be assembled with the top, and to automatically adjust to fit perfectly against the flange 30 of the top and to bear closely and strongly upon itself at the point of overlap as indicated at numeral 32. Moreover, since the inner burner tube may close upon itself, i.e. slip relatively end-to-end at the overlap, the overall expansion of the heater as the metal becomes hot is automatically compensated for, and otherwise consequent damage is avoided due to buckling and similar heat deformation. Also, and very importantly, the dimension relationship between the points of top and tube contact is closely maintained so that the vent spaces 28 are maintained substantially constant and fumes are thereby certainly prevented from building up to a dangerous level. The described burner tube construction has a further important purpose which is to permit a large number of tubes to be stored in off season in a minimum of space. As will be understood, when a tube is removed from the heater position, it springs open to an extent, thus enabling ready grouping together a very large number of tube bodies in wall to wall relationship.

As will be seen, the burner tube 20 rests loosely on the bottom 18, it not being essential to have machined fit, and in fact, preferably not so, in order that oil may easily move under the tube lower edge as oil is burned in the tube. If desired, the tube wall may be notched to provide an oil passageway from the reservoir to the tube inside, but such is not necessary.

Referring more particularly to the spaces 28 which vent the reservoir, it will be noted that they are the sole points of egress, or ingress, provided for the reservoir. From this construction flows a most important combination of advantages, notable among which are increased fuel and labor economy, increased safety and relief from the danger of explosion, and assured continuity of operation which is essential to grove protection.

In providing vent spaces 28, it will be seen that hydrocarbon vapors which build up within the reservoir are constantly caused to discharge adjacent the flame area, this being intended according to the invention, since it has been found that such vapors are burned about the periphery of the tube upper end. Burning of the hydrocarbon vapors not only adds significantly to the total heat output in the grove considering the fact that hundreds of them might be in operation, but, also, they are consequently not freely released into the atmosphere as noxious impurities. It has been found to be important to gauge the total vent area so as to surely maintain a persistent and continuous discharge through the vent spaces, because, by so doing, it is made certain that a combustible mixture cannot develop in the reservoir; in other words so long as vapor is discharging at a steady rate of flow, air cannot enter the space above the oil. Of course, this flow relieves the vapor pressure above the oil and, moreover, although it is not likely that excessively high pressure would develop, if for any reason the tendency to high pressure should occur, such would be relieved by the ability of the burner tube 20 to constrict itself and thereby provide a somewhat larger vent area. Thus, the burner tube itself may act as a pressure relief valve. For example, in employing a gene-rally circular reservoir of about nineteen ('19) inches in diameter, an inner burner tube of about ten inches diameter, the heater using a fuel such as a No. 2 diesel or grove oil, the vent spaces should not be wider than about inch (radial measurement of the spaces) for practical and assured good results. Obviously, within limits at larger diameter reservoir, with consequent greater oil surface area potentially permits a higher quantity of vapors to be generated and, therefore, if vapor quantity increases a somewhat larger spacing may, if desired, be adopted. For practical grove use, however, the above dimensions, which provide a reservoir capacity of approximately nine galions, are found to be appropriate. These dimensions will assure continued burning of the grove heater for about 10 to hours depending upon whether or not the burning rate is reduced by the regulator ring (yet to be described).

As will be observed, the annular flange 30, provided on top cover 22, which serves as a water barrier, also serves to deliver the vapor issuing from the reservoir upwardly so that the vapors are not diffused significantly and reach a point where they will readily be ignited.

It is important to recognize that in providing a grove heater, one is not prescribing for an ordinary single unit requirement because such heaters are employed in large numbers and, consequently, constructions that might appear to be somewhat inelegant, for that matter, crude, when viewed in the light of the modern, are to a great extent dictated by the number which is involved, and the speed with which they must be attended under highly adverse conditions by unskilled labor. The provision of an ideal heater unit which is to be coordinated into a multiple heating system presents a challenge of considerable magnitude.

Referring again to the rate of vapor generation, the major volume thereof by a great factor is gene-rated in the vicinity of the outer surface of the inner burner tube where it is hottest. The body of oil surrounding the tube is always hotter than that at the peripheral surface of the reservoir although the latter does become hot es pecially when the volume of oil is small. Since the volume of oil grows less as the supply thereof is depleted, it is apparent that oil temperature in the total volume will rise measurably, especially if the burning rate continues at a high level. Therefore, it will be seen that both the rate and quantity of vapor production will vary greatly under these normally changing conditions. The burning rate may be controlled by placing regulator 12 in position on the top surface of the burner tube. This regulator consists of a simple circular metal plate 36 having a circular opening 38 at its center. In other words,

somewhat like a doughnut. Numeral 4i) denotes a downwardly turned annular flange which serves to position the regulator. It may be designed if desired to have a variable center opening so that theburning rate can be controlled over a wide range; moreover, if desired a number of such regulator's having. different size central openings may be employed with the same objective. However, actual conditions do not ordinarily require a high degree of selectivity in this respect and practical needs are found to be adequately served by a regulator which cuts the rate to approximately fifty percent (50%) of the possible maximum.

Burning rate, however, is often quite affected by high Wind conditions and on these occasions vapor generation can be expected to increase. Therefore, considering the number of factors which enter into the equation for assured and safe continuity of burning of a large number of burners in simultaneous operation, it becomes a difficult matter to prescribe an infallible construction.

Considering the foregoing discussion concerning the discharge of the hydrocarbon vapors from the reservoir, it will be perceived by those skilled in the art that an objective of this invention is to maintain an internal pressure within the reservoir substantially above ambient pressure conditions taking into account momentary changes therein as brought about by wind conditions and the like. Obviously, in order to accomplish this objective the top 22 of the reservoir must have sufficient weight to effect the desired pressure conditions within the reservoir, or must fit tightly enough on the reservoir itself to prevent the entrance of sufiicient air to produce possible explosive condition. Thus, it is important that an air draft not be set up between the vent area and the outer top edge.

Further referring to FIGURE 2, as is heretofore indicated, numeral M denotes what is termed a rain cover. As is plainly indicated in the drawings, the cover comprises nothing more than a simple cap which fits over the burner tube and acts as a shield not only to prevent rain from being introduced into the heater but also shields against falling debris from the trees. The cap is provided with a down-turned flange 42, the flange seating upon the top of the reservoir.

The heater units of this invention may be constructed of any suitable material, such as steel or aluminum. Obviously aluminum has the advantage from the standpoint of weight and, while it is not as resistant to damage by rough use as is steel, it is sufficiently so to be quite practical. Moreover, aluminum is quite weather resistant and consequently there is no rust problem. However, construction of galvanized sheet steel of proper gauge is perfectly satisfactory.

In use, the heaters of this invention preferably are started on a low-fire level, that is to say, with the regulator ring in place, unless it is necessary to introduce a large quantity of heat into the orchard or grove immediately. Generally, however, there is sufficient notice of approaching cold Weather that the heaters may be started on the low-fire basis in advance of the actually potentially damaging cold and thereafter advanced to full heat capacity by simple removal of the regulator rings.

While the invention has been described in detail and with reference to particular shapes and forms, it is obvious that modifications of the teachings herein may be made without departing from the spirit of the invention. For example, the parts have been described as round in nature. Obviously a square or other shape reservoir and cooperating parts may be employed. The flutes which are provided in the burner tube wall may alternatively and similarly be formed along the inner rim of the flange surface of the reservoir top, thereby maintaining the desired space relationship between the burner tube and the reservoir top. The units may 'be provided with leveling devices if desired. Many other modifications may be envisioned within the skill of the art.

What is claimed is:

1. A heater especially adapted for outdoor use in the protection of orchards, groves and the like, comprising a fuel reservoir having side walls, a bottom wall and a top cover, said top cover having a central opening therein, said central opening constituting the sole opening in said top and said top fitting closely upon said reservoir, said reservoir being of continuous construction having no openings to the atmosphere in its walls; an upstanding burner tube, positioned in its working position on said bottom wall within said reservoir and centrally thereof, said tube extending through said opening to a point above the upper surface of said top, said tube being formed from a metal blank of a springy nature and having overlapping ends when in shaped tube form and in working position, said metal tube having upstanding flute-like portions in its walls to thereby provide restricted space about the periphery of said tube for passage of vapors generated in the fuel reservoir to a point above the level of said top, and generally into the area immediately adjacent the top of said tube, whereby said vapors are consumed as a result of ignition of oil undergoing combustion within the confines of the said tube; the spring force of said metal tending to open said tube and thereby hold it firmly in position against said top at the flute like portion; said space having its horizontal area predetermined in relation to vapor generation within said reservoir and effecting vapor pressure build-up within said reservoir substantially above atmospheric pressure and persistent flow of vapors therefrom.

2. A heater as claimed in claim 1 wherein means are provided for varying the quantity of oxygen entering the burning zone of said burner tube whereby the rate of heat delivery is controlled.

3. A heater as claimed in claim 2 wherein said means are provided in the form of a plate having a central opening therein and adapted to fit over the upper edge of said burner tube whereby the inflow of air into the burner tube is restricted in accordance with the area of said opening and the burning rate of fuel is regulated correspondingly.

References Cited by the Examiner UNITED STATES PATENTS 1,079,645 11/ 1913 Hamilton 15891 1,100,101 6/1914 Scheu 158-91 1,815,388 7/1931 Witt 15891 2,458,916 1/1949 Peter 158-28 FOREIGN PATENTS 232,182 6/1925 Great Britain. 527,286 10/ 1940 Great Britain.

FREDERICK KETTERER, Primary Examiner. 

1. A HEATER ESPECIALLY ADAPTED FOR OUTDOOR USE IN THE PROTECTION OF ORCHARDS, GROVES AND THE LIKE, COMPRISING A FUEL RESERVOIR HAVING SIDE WALLS, A BOTTOM WALL AND A TOP COVER, SAID TOP COVER HAVING A CENTRAL OPENING THEREIN, SAID CENTRAL OPENING CONSTITUTING THE SOLE OPENING IN SAID TOP AND SAID TOP FITTING CLOSELY UPON SAID RESERVOIR, SAID RESERVOIR BEING OF CONTINUOUS CONSTRUCTION HAVING NO OPENINGS TO THE ATMOSPHERE IN ITS WALLS; AN UPSTANDING BURNER TUBE, POSITIONED IN ITS WORKING POSITION ON SAID BOTTOM WALL WITHIN SAID RESERVOIR AND CENTRALLY THEREOF, SAID TUBE EXTENDING THROUGH SAID OPENING TO A POINT ABOVE THE UPPER SURFACE OF SAID TOP, SAID TUBE BEING FORMED FROM A METAL BLANK OF A SPRINGY NATURE AND HAVING OVERLAPPING ENDS WHEN IN SHAPED TUBE FORM AND IN WORKING POSTION, SAID METAL TUBE HAVING UPSTANDING FLUTE-LIKE PORTIONS IN ITS WALLS TO THEREBY PROVIDE RESTRICTED SPACE ABOUT THE PERIPHERY OF SAID TUBE FOR PASSAGE OF VAPORS GENERATED IN THE FUEL RESERVOIR TO A POINT ABOVE THE LEVEL OF SAID, AND GENERALLY INTO THE AREA IMMEDIATELY ADJACENT THE TOP OF SAID TUBE, WHEREBY SAID VAPORS ARE CONSUMED AS A RESULT OF IGNITION OF OIL UNDERGOING COMBUSTION WITHIN THE CONFINES OF THE SAID TUBE; THE SPRING FORCE OF SAID METAL TENDING TO OPEN SAID TUBE AND THEREBY HOLD IT FIRMLY IN POSITION AGAINST SAID TOP AT THE FLUTE LIKE PORTION; SAID SPACE HAVING ITS HORIZONTAL AREA PREDETERMINED IN RELATION SPACE HAVING ITS HORIZONTAL AREA PREDETERMINED IN RELATION TO VAPOR GENERATION WITHIN SAID RESERVOIR AND EFFECTING VAPOR PRESSURE BUILD-UP WITHIN SAID RESERVOIR SUBSTANTIALLY ABOVE ATMOSPHERIC PRESSURE AND PERSISTENT FLOW OF VAPORS THEREFROM. 